On Thu, 16 Jun 2005 22:23:58 GMT, "Pete C."
wrote:

Eric R Snow wrote:

On 16 Jun 2005 13:33:14 -0700, "
wrote:

I don't know what DC voltage a mag chuck needs. So you might need a
transformer in addition to the lamp dimmer and rectifier.
Dan
Oh. The mag chuck needs 100 vdc. Part of the reason for the dimmer is
to limit the voltage to the chuck. But I suppose a transformer would
be OK. I just want to know if a rectifier connected to something that
expects a resistive load will ruin the device.

The lamp dimmers use phase control dimming with triacs. They turn on the
triac part way into the half cycle of the AC, so they do not in any way
limit the peak voltage.

They actually eliminate the first part of the waveform rising (or
falling) from the zero crossing point, generating quite a switching
transient which is what causes filament buzz.

Try a variac (variable autotransformer), they will actually reduce the
voltage supplied to your rectifier.

Pete C.
So the dimmers keep more and more of the waveform on either side of
the peak as the power is increased? And they always reach peak
voltage? I thought that they started conducting at zero and used more
and more of the voltage until peak voltage is reached. But after
reading your post that doesn't make sense to me.
Eric